Roger has always claimed that one day he'd like to win the Davis Cup as well.
As it so far has never been very likely that Switzerland would get very far at all, despite having Feds in their team at times (just to keep 'em in the World Group that is
) - one Top Player is just not enough to get you there - things might have just changed a little bit in the positive direction for them now that they have a second top ten player with Stan on board, and even more, one that matches up with Fed in the doubles very well as well.
So my guess is that even while it's still unlikely for them to win it (at least I think so), I don't doubt that Fed will indeed be more committed to it. Grab your chances when they come along!